The newly-promoted side will face United at Old Trafford on Sunday.
“They’ll have a lot of ambition and will want to show people they deserve to be in the Premier League,” Evra is quoted on the club’s official website as saying.
“It’s often hard playing teams who have just been promoted or teams in the bottom half of the table because they have nothing to lose.
“If Birmingham get beaten it’s not a big deal – most people would expect them to lose against the champions.
“So they’ll play freely and without fear. We might see them play some good football and this is why it won’t be easy.”
“I can’t wait [to run out on Sunday],” he added.
“Footballers don’t have the longest holidays, but when you’re not playing it seems like forever.
“It’s important we continue our good pre-season form, get three points and start the season well.”